Low volume spray method



April 14, 1970 Filed May 15, 1968 J. E. WALDRUM 3,506,195

LOW VOLUME SPRAY METHOD 2 Sheets-Sheet 1 INVENTOA? JOHN WALDRUM 2 @fmlu,

ATTORNEYS.

April 14, 1970 J. E. WALDRUM 3,506,195

LOW VOLUME SPRAY METHOD Filed May 15, 1968 I 2 Sheets-Sheet 2 PR/O/QART.32 0g 30 30 (a: o

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ATTORNEYS.

United States Patent 3,506,195 LOW VOLUME SPRAY METHOD John E. Waldrum,Ambler, Pa., assignor to Amchem Products, Inc., Ambler, Pa., acorporation of Delaware Continuation-impart of application Ser. No.648,462, June 23, 1967. This application May 15, 1968, Ser.

Int. Cl. B05b 17/04 US. Cl. 239-11 9 Claims ABSTRACT OF THE DISCLOSUREThe present application is a continuation-in-part application based oncopending application Ser. No. 648,462, filed June 23, 1967, now PatentNo. 3,399,638 granted Sept. 3, 1968.

This invention relates to a method for applying low volumes of liquidssuch as agricultural sprays as exemplified by herbicides. In particularthe invention is devoted to a method of applying low volumes ofconcentrated materials in an extremely uniform way.

The spraying of active materials generally is accomplished through theuse of such materials in dilute form. This is because a dilute sprayalmost necessaril insures av uniform coverage. Relatively minorvariations in flow rate or even in compounding are not significant inview of the dilute nature of the material being sprayed and therelatively high volumes under which spraying occurs.

In applying herbicides, similar practices are used. In particular it isquite normal to apply herbicidal mixtures at rates from 10 to 100gallons per acre and sometimes even higher. In view of these largevolumes, the only practical solvent is water, and thus, where the activeingredient is not soluble with water, additional difiiculties arise withit being necessary to create some type of solution or emulsion which canbe admixed with water.

Obviously, the handling of large volumes of liquid adds considerably tothe expense of the spray operation. Furthermore, with systemicherbicides there is the problem of drift since the large spray rates andthe use of high pressure atomizing nozzles necessarily creates many finedroplets which can be carried away by normal wind currents to unwantedareas.

A.. seemingly logical solution to the foregoing problem is to try toapply herbicides in concentrated form, but this type of spray method haslargely proved to be unsuccessful, at least in the case of herbicides,in view of the requirement for uniform spray. Concentrated materialslike insecticides have been applied with an atomizing spray, but herethe production of fine particles does not present a problem since anymisdirected particles of insecticides do not normally produce the deadlyresults of a systemic herbicide where even a few droplets can killcertain types of economic crops in a neighboring field.

In the case of a concentrated herbicide, if too little of the herbicideis applied, no herbicidal effect will be achieved. If too much herbicideis applied the excess is not only expensive, but there could be anadverse effect upon the economic crop.

In view of the foregoing, it has long been the practice to applyherbicides in dilute form since this at least achieves better control ofthe rate of application-although creating considerable expense in thelarge equipment that is necessarily required, as well as alwayspresenting the ever present problem of a satisfactory water supply.

In addition to the foregoing, the farmer normally pur chases theherbicide in concentrated form. He then has to become involved with theexpense and trouble of admixing the herbicidal concentrate with largevolumes of water. Where the herbicide is not sufliciently water soluble,it will also have to be formulated to prepare it for mixing with water.

It is therefore a prime object of the present invention to provide a lowvolume spray method where ideally the farmer will be able to purchasethe herbicide in concentrated form and simply use it in that form, andthereby eliminate the time, expense and trouble which for many years hasbeen an accepted part of the farmers duties.

While the present invention is to be described in terms of concentratedherbicides, it is to be understood that the low volume spray methodhereinafter described and claimed is suitable for use for otherpurposes, and while concentrated liquids are preferably used in thepresent low volume spray method, it is to be recognized that the presentinvention even has application with dilute liquids where a uniformapplication rate is to be maintained.

Yet another object of the present nvention is to provide a low volumespray method which will effect tremendous savings, and yet at the sametime will bring about simpler techniques for the farmer.

The foregoing as well as other objects of the invention are achieved byproviding a low volume spray method, for use in applying concentratedherbicides at a rate of from about A to 2 gallons per acre (from about 1drop per 2 square inches to about 5 drops per square inch), wherein theconcentrated liquid is discharged at a distance from 1 to 18 inchesabove the target area, with at least of the droplets so dischargedhaving a diameter of at least 400 microns. In a preferred form of theinvention there should be applied at least /2 gallon per acre (producingabout 1 droplet per square inch), the application being made from aheight of at least about 4 inches.

Other objects and many of the attendant advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description.

The method of this invention may be effected in a number of differentways, usually by employing specialized spraying apparatus. A particularexample of one type of such apparatus is that described and claimed inmy copending application Ser. No. 648,462, filed June 23, 1967, theconstruction and operation of which will now be summarized withreference to the accompanying drawings wherein:

FIG. 1 is a partially schematic view showing a spray system applyingconcentrated herbicide in accordance with the low volume spray method ofthe present invention;

FIG. 2 is a view showing particle size distr bution as obtained throughthe use of prior art atomizers; and

FIG. 3 is a view similar to FIG. 2 but showing the particle sizedistribution obtained in producing the low volume spray method of thepresent invention.

Reference is now made to FIG. 1 of the drawing, wherein like referencecharacters refer to like parts, which shows a preferred spray systemthat may be used to carry out the low volume spray method of the presentinvention. It is to be emphasized that other spray systems could bedevised to carry out the low volume spray method of the presentinvention, and that even the simple use of a source of liquid and aspray head with appropriate constant head bands under proper controlcould achieve the iniforrnity as well as the other requirements of thelow 'olume spray method of the present invention.

As shown in FIG. 1 a tank or reservoir 12 is provided 11 order to hold asupply of a concentrated agricultural iquid (like a herbicide) to bedischarged through tubing [6, motor 18, then to rotating spray nozzle 20and finally )ut through the four spray ports 24. It is to be noted thathe spray nozzle 20 is positioned close to the ground 22 that the sprayports 24 of the nozzle 20 are positioned it a distance from 1 to 18inches above the ground.

The droplets emanating from nozzle 20 are rather large 11 size, with atleast about 95% of such droplets having a liameter greater than 400microns and less than 2000 nicrons. This large particle size, as well asthe extreme iniformity of spray rate, achieved by means of ma nainingthe discharge rate of liquid 14 through tubing 16 :onstant withessentially no variation irrespective of the Jeight of the liquid 14 inthe tank 12.

The liquid is led to a spindle (not shown) extending nto motor 18 withthe spindle having a bore to define r flow path for the agriculturalliquid, and the spindle is rotated about an axis at a predetermined rateof the order )f about 1000 rpm,

Further details of the spray apparatus of FIG. 1 are ;et forth inaforesaid Patent No. 3,399,638, the disclosure at which is incorporatedby reference. It is to be under- ;tood that the relatively large anduniform droplet pat- :ern of the present invention being applied at thespecified iistance above the ground at a very constant rate can beachieved by hand or by other apparatus which would occur to thoseskilled in the art.

It is possible to achieve the relatively large droplet size Jy providingenlarged openings in the discharge nozzles of devices on the market,although the elimination of fine droplets is a matter of careful design.

Similarly, where a constant head feature is not to be incorporated intothe apparatus, variations in discharge rate due to a changing head ofliquid will have to be :ompensated for in some way, such as an overflowtype tank which is in reality another form of a constant head device.

Reference is made to FIGS. 2 and 3 of the drawings which compare thespray pattern of a typical prior device with a spray pattern achievedwith the present invention. FIG. 2 shows the spray pattern of a priordevice which will contain large droplets 30, intermediate droplets 32and fine droplets 34.

The fine droplets will, of course, tend to drift under normal aircurrents, and where the number of fine droplets is excessive there couldbe not only a substantial effective decrease in the rate of applicationwhere low volumes of liquids are being applied, but also there could beextensive damage to surrounding crops.

FIG. 3 shows the spray pattern achieved by the method of the presentinvention wherein the droplets 36 are essentially large, and wherein 95%of such droplets fall within the range of 300 microns to 2000 microns.

It is preferred that the lower range of droplet size start at 500microns, and for the sake of uniformity the liquid should be applied sothat there is deposited at least one drop per square inch,

The details of the spray system 10 of FIG. 1 are disclosed and claimedin copending appl cation Ser. No. 648,462, filed June 23, 1967, and havebeen summarized only, but the disclosure of said application Ser. No.648,-

462 is hereby incorporated by reference and considered a part hereof.

Uniformity of spray rate is very important in the successful applicationof concentrated herbicides. Also, there is the combination of largeparticle size and closeness to the ground which prevents undesirabledrifting of the particles,

It has been determined that liquid particles having a diameter less than400 microns are more susceptible to normal air currents than largerdroplets, so it is a requirement of the present invention that at leastabout of the droplets sprayed have a diameter of at least 400 micronsand preferably more.

Indeed, in order to obviate completely the possibility of separativedrift under normal wind conditions, minimum droplet size of at least 500microns is preferred. Furthermore, it is recommended that, in general,the droplet size be increased as the application height is increased.Thus, when spraying 4 inches from the target area a droplet size of 500or 600 microns is quite satisfactory, however, when spraying from 18inches, a droplet size of at least 1000 microns is recommended.

It has been determined that a workable upper limit for the particle sizeis about 2000 microns. Beyond this there is the danger that theextremely large droplet will itself subdivide, and thus produce unwantedfines.

As stated above, the spray method of this invention involves controlledspray application from a distance of from 1 to 18 inches from the targetarea, preferably of from at least 4 inches. These minimum distances arepractical limitations, dictated by the area which is being sprayed. Forexample, when spraying very fiat areas, it is possible to apply theliquid from a height as low as 1 inch.

However, the target area-for instance, a plowed field or a crop-israrely uniformly flat, and therefore a minimum spray distance of about 4inches is preferred in order to avoid damaging the applicator and inorder to effect as uniform as possible a spray rate on the target. Themaximum distance from the target area is set at about 18 inches, becauseat distances higher than that it becomes dlfilClllll to control overalldriftas opposed to separative drift-of the spray.

Furthermore, since even the best spraying apparatus will produce somesmaller-than-average droplets, there may in practice be minor problems,at a distance greater than 18 inches, in preventing separative drift.Finally, since any droplet will tend to evaporateand thus grow smallerasit travels to the target area, the maximum distance of 18 inches isrecommended to avoid this problem so as to reduce the resultingseparative drift which could well occur.

Naturally a drop much smaller than 400 microns which has a considerabletime in its flight pattern, could in some cases become extremely smalland thus float for considerable periods of time and thereby be morelikely to be carried by air currents or wind to an undesirable place.

The following test results are now given, though without any limitativeeffect, to demonstrate the advantages of the present invention overspray methods or" the prior art.

In a typical spray achieved by the method of the present invention, thefollowing distribution of spray droplets was obtained as set forth inTable 1.

TABLE 1.SIZE-FREQUENCY DISTRIBUTION OF SPRAY DROPLETS (PERCENT) NozzleDiameter in microns. 1 2 3 4 5 Less than 300 0 1 0 0 "6 301-400 0 5 0 l21 401-500. 0 0 1 0 28 501-600. 3 3 3 4 17 601-700- 13 23 1 5 11701-800- 17 24 2 7 8 801-900 25 15 19 17 5 901-1300..-- 25 10 20 12 21,00l1,100 10 8 13 17 2 1,1011,200 2 9 25 16 0 1,201-1,300 2 0 6 6 01,301-1,40 0 0 4 5 0 Greater than 1,401 0 0 5 10 0 Percent over 400 94100 99 27 Percent over 500 100 94 99 99 55 1-Low volume nozzle, 6 x.016" openings.

2-Low volume nozzle, 6 x .020 openings. 3Low volume nozzle, x .024"openings.

4Low volume nozzle, 4 x .033 openings.

5Atoniizing nozzle.

A considerable number of particles were formed by this atomizing nozzlethat were so small they floated away before their size and number couldbe recorded.

This distribution test was madeusing the.,apparatus described herein. Itwill be observed that, even-when using apparatus specifically designedto give as uniform a spray as possible, there is still a distribution ofdrop sizes-in this case the average drop size (an average which appliesto about 60% of the spray) is in the narrow range of 600 to 1200microns, and that, with any particular nozzle, the main part of thespray is composed of droplets having a diameter within a range whichextends only over 400 microns.

In order to demonstrate the effectiveness of the low volume spray methodof the present invention a sprayer like that shown in FIG. 1 was fittedwith a spray head to give a inch spray band and spray rate of fourgallons per acre on a broadcast basis.

TEST 1 The application was made from a height of 5% inches using a No. 3nozzle (see, Table I). The majority of the droplets were in the sizerange 400 to 1200 microns.

The herbicide employed was Amiben (3-amino-2,4-dinitrobenzoic acid) at aconcentration of one pound per gallon of water.

The test flats were first seeded with a mixture of pig weed, velvet leafand barnyard grass and covered with a /2 inch layer of soil, and thenthinly sprayed. The application ratewas 4 pounds per acre (4 gallons ofconcentrate per acre). Fourteen days later the following results wereobserved:

TABLE II Speed of mate speed Percent Control ofspray cart of spraym.p.h.) disc (r.p.rn.) Barnyard grass Pigweed Velvet leaf (stunted &

chlorotic) 7 a:At this speed the'spray rate was 3 lbs. per acre ratherthan 4 lbs. per re.

. The untreated, control test flats all showed vigorous Weed growth. I

The tests of Table II show excellent weed control employing the lowvolume spray method of the present invention. Furthermore, the herbicidewas effective over large areas on a uniform basis.

TEST 2 Tests similar to that described just above have been carried outusing other herbicides, in particular: Fenac (the sodium salt of2,3,6-trichlorophenylacetic acid, in an aqueous medium); Sindone-B(1,1,4-trimethyl-6-isopropyl-S-indanylethyl ketone in an acetonemedium); Atrazine (2-chloro-4-ethylamino-6-isopropylamino-l,3,5-triazine in an N-methyl pyrrolidone medium); Pyramin (5amino-4-chloro-2-phenyl 3-(2-H)-pyridazinone, in an N-methyl pyrrolidonemedium); Diuron (N-(3,4-dichlorophenyl)-N',N'-dimethylurea, in anN-methyl pyrrolidone medium); and the methyl ester of Amiben (in anacetone medium).

The results of these tests are shown in Table III below.

These tests were put down on a soil that varied from a clay loam to aSanta Isabel clay. The area was rotovated before application and amixture of weed seed was broadcast over the test area (rye grass,barnyard grass, pigweed, mustard and cotfeeweed) The sprayer was mountedbehind a commercial planter used for planting tomatoes. Soybeans wereplanted into all test rows. All of the mate rials were applied as 2 lb./gal. formulation. The sprayer was adjusted to give an 18-inch band witha delivery from the nozzle of 28 ml./ min. The tractor speed was 1 mphThis gave a rate on a broadcast basis of 4.9 lbs/A. at

6 a volume of 2.45 gal/A. Overhead irrigation was applied as follows:

2.5" on 1-11-67 1.5" on 1-20-67 1.5" on 1-27-67 1.6" on 130-67 (rain)TABLE III Average percent control Rye- Barn- Pig- Cofiee- Chemical grassyard weed Mustard weed Amiben (water Solvent) 100 100 100 100 100 Fenae,Na salt (water solvent) 100 100 100 100 100 Sindone-B (acetone solvent)100 90 100 40 2O Amiben, methylester (acetone solvent). 90 100 100 60Diuron (N-methyl pyrrolidone solvetit) 100 100 100 100 100 Atrazine (Nmethyl pyrrolidone solvent) 100 100 100 100 100 Pyramin (N=methylpyrrolidone solvent) 70 90 All of these plots gave a clearly marked18-inch band of weed control. There wasexcellent weed growth justoutside the treated band. Within the band there was no indication of anyskipped area. There was no injury to the soybeans in the Amiben, Amibenmethyl ester, or Sindone-B plots.

Where any herbicide has shown itself to be selective in the dilute form,it has indicated similar favorable selectivity in the concentrated formwhen applied in accordance with the low volume spray method of thepresent invention.

v The effect of wind on the spray method of the present invention hasalso been demonstrated. A comparison is made in Table IV of resultsobtained in static air conditions with results obtained in a six mileper hour crosswind, as well as of the results obtained for the method ofthe invention, with those of a prior art method. In order to determinedrift effects, tomato plants were set downwind from the respectiveSprayers at a distance of approximately three feet from the spraynozzle. The weeds sprayed were mustard, pigweed and crabgrass. Theherbicide was Amiben, and was sprayed from a .distance'of 5% inches, togive a 10-inch wide band, using a No. 3 nozzle (see Table I). Theresults were as follows: I H

- f TABLE IV 1. Sprayer of present invention (pm-emergence weed control)v 7 Average percent weed control Tomato Wind Rate (m.p.h.) EpistanyMustard Pigweed Crabgrass 2 lbs./A 0 O 87 100 100 2 lbs/A... 6 5 83 10C)100 4 lbs./A 0 0 100 4 lbs. /A 6 5 95 100 100 2. Conventional atomizingsprayer (pro-emergence weed control) Average percent weed control WindTomato Rate (m.p.h.) Epistany Mustard Pigweed Crabgrass 2 lbS./A 0 7. 545 65 60 2 1bs./A 6 4O 35 40 40 4 lbs./A 0 10 85 90 90 nendously with acrosswind. Indeed the epistany effect n the tomatoes shows clearly thatenough spray was caried away, as drift, to seriously damage neighboringplants. Vith the present invention, however, there was no signifi- :antamount of drift, even with the crosswind.

It is to be understood that a wide range of herbicides :an be applied inconcentrated form in accordance with he method of the present invention.Such herbicides in- :lude, without limitation, 2,4-dichlorophenoxyaceticacid, L,4,S-trichlorophenoxyacetic acid and Amiben.

The broad range of herbicides that can be sprayed in lccordance with themethod of the present invention are :ollectively referred to in theclaims as agricultural prays. However, this term is not necessarilylimited to ierbicides since it may encompass other active agents likensecticides and fungicides. Furthermore, this term is not iecessarilylimited to concentrated liquids, although the nethod of the presentinvention is generally carried out ising concentrated liquids.

The present invention also contemplates applying the agricultural spraysat a distance from 1 inch to 18 inches lbOVC the ground or away from atarget area at a very :onstant rate. The precise distance above thetarget area will depend upon the type of spray equipment being used aswell as the ability to work in close to the target area which in somecases may be hindered by vegetation.

It will be understood that the distance from which the spray is appliedand the size of the droplets sprayed depend on a number of features. Inparticular they can depend on the liquid being sprayed and the materialonto which it is sprayed. For example, many herbicides are extremelyinsoluble in water, and will not extend laterally over the ground orplant they are sprayed on. Furthermore, various types of earth canprevent satisfactory dispersion of a sprayed liquid. For example, whenspraying an easily absorbed liquid it is suflicient to spray large dropsat a rate of about one in every 2 square inches. When sprayinghard-to-absorb liquids, however, it is more convenient to employ smallerdrops at a rate of four or five drops per square inch (while the amountof active ingredient per acre remains, of course, the same).

It is therefore seen that the present invention provides a method forapplying low volumes of liquid, preferably concentrated herbicidalliquids, to undesired vegetation.

In so doing, the expense and trouble of handling large volumes ofliquids is essentially eliminated, and the entire spraying processgreatly simplified.

Without further elaboration, the foregoing will so fully illustrate ourinvention that others may, by applying current or future knowledge,adopt the same for use under various conditions of service.

What is claimed as the invention is:

1. A low volume spray method for applying agricultural spray to a targetarea, said method involving applying said spray at a distance from 1inch to 18 inches away from said target area at a very constant rate,the droplets in said spray being relatively large with at least of saiddroplets having a diameter greater than 400 microns and less than 2000microns.

2. The invention of claim 1 wherein 95 of said droplets have a diametergreater than 500 microns and less than 2000 microns.

3. The invention of claim 1 wherein said droplets are applied in acoverage of 1 drop per 2 square inches to 5 drops per square inch to thetarget area.

4. The invention of claim 3 wherein said droplets are applied in acoverage of 1 drop per square inch to the target area.

5. The invention of claim 1 wherein said spray is applied at a rate from/1 gallon per acre to 2 gallons per acre.

6. The invention of claim 5 wherein said spray is applied at a rate of/2 gallon per acre.

7. The invention of claim 1 wherein said distance is at least 4 inchesand not greater than 18 inches.

8. A low volume spray method for applying agricultural spray to a targetarea, said method involving applying said spray at a distance from 4inches to 18 inches away from said target area at a very constant rate,the droplets in said spray having a diameter greater than 500 micronsand less than 2000 microns, with said spray being applied to the targetarea at a rate of from /2 gallon per acre to 2 gallons per acre.

9. The invention of claim 8 wherein said droplets are applied in anaverage coverage of about 1 drop per square inch to about 5 drops persquare inch.

References Cited UNITED STATES PATENTS M. HENSON WOOD, JR., PrimaryExaminer J. I. LOVE, Assistant Examiner US. Cl. X.R.

